Abstract

Giant magnetoresistance (GMR) head technology is one of the latest advancements in the hard disk drive (HDD) storage industry. The GMR head multilayer structure consists of alternating layers of extremely thin metallic ferromagnetic and nonmagnetic films. A large decrease in the electrical resistivity from antiparallel to parallel alignment of the film magnetizations is observed, known as the GMR effect. The present work characterizes the in-plane electrical and thermal conductivities of Cu∕CoFe GMR multilayer structures in the temperature range of 50K to 340K using Joule-heating and electrical resistance thermometry on suspended bridges. The thermal conductivity of the GMR layer monotonically increases from 25Wm−1K−1 (at 55K) to nearly 50Wm−1K−1 (at room temperature). We also report a GMR ratio of 17% and a large magnetothermal resistance effect (GMTR) of 25% in the Cu∕CoFe multilayer structure.

Schematic representation of electron transport in a GMR multilayer structure, consisting of top and bottom CoFe magnetic layers and Cu nonmagnetic space layer. The distance between the layers is relatively small compared to the mean free paths of electrons. Large decreases in the electrical and thermal resistivities are expected due to the spin-dependent scattering at the interfaces of the CoFe and Cu multilayer structure.

The fabricated suspended microbridge structure: (a) schematic, and (b) top view image taken using an optical microscope. The dimension ΔL is the length of the over-etched area near the bases of the suspended structure. Voltage pads are connected to the suspended structure by nearly 2‐μm‐wide interconnects.

Changes in the electrical resistances of the suspended bridge as a function of square of current, I2. Curve fits for bridges of the same width and different lengths yield kGMR=51Wm−1K−1, for the GMR layer.

Schematic of the calibration procedure. The R versus I curves for the GMR bridge were measured at different field strength while keeping the base temperature constant. The same process was repeated at different base temperatures.

Copyright in the material you requested is held by the American Society of Mechanical Engineers (unless otherwise noted). This email ability is provided as a courtesy, and by using it you agree that you are requesting the material solely for personal, non-commercial use, and that it is subject to the American Society of Mechanical Engineers' Terms of Use. The information provided in order to email this topic will not be used to send unsolicited email, nor will it be furnished to third parties. Please refer to the American Society of Mechanical Engineers' Privacy Policy for further information.

Shibboleth is an access management service that provides single sign-on protected resources.
It replaces the multiple user names and passwords necessary to access subscription-based content with a single user name and password that can be entered once per session.
It operates independently of a user's location or IP address.
If your institution uses Shibboleth authentication, please contact your site administrator to receive your user name and password.